In manufacturing a device such as a semiconductor device, a process of filling silicon into a recess such as a through-hole or a contact hole is performed. The silicon filled into the recess may be used as, for example, an electrode.
Specifically, in such a filling process, a polycrystalline silicon film is formed on a wall surface defining a trench in a workpiece. Thereafter, an amorphous silicon film is formed on the polycrystalline silicon film. Subsequently, the workpiece is annealed. In the filling process, the annealing of the workpiece allows the amorphous silicon to move toward a bottom portion of the trench, thus filling the trench with the amorphous silicon.
The recess may be formed to penetrate an insulating film and extend to an inside of a semiconductor substrate used as an underlying layer of the insulating film. The recess is formed by etching the insulating film and the semiconductor substrate. The present inventors have studied a technique for filling a recess by movement of a semiconductor material toward a bottom portion of the recess; and crystallizing the semiconductor material of the semiconductor substrate to form an epitaxial region.
In this study, the present inventors have found that a region that causes damage by etching (hereinafter, referred to as a “damage region”) is sometimes formed on a surface defining the recess in the semiconductor substrate, which fails to undergo an epitaxial growth at the damage region, thus generating a cavity such as a void in the recess.